Overvoltage protection circuits are used to protect electrical or electronic circuits that can be damaged if subjected to overvoltage conditions such as caused by voltage transients, voltage spikes, electrical discharge, etc. Overvoltage conditions at a certain electrical point in an electrical circuit, such as an electrical connection point, pin of an integrated circuit, a certain input or output in a system, etc. can cause electrical circuits to become damaged and fail to perform their normal function.
Some prior art overvoltage condition protection circuits have included the use of metal oxide varistor (MOV) for protecting against high voltage conditions. MOVs however degrade over time and sometimes fail by creating a partial or complete short circuit of the line being protected and thereby affect the operation of the circuit being protected. Another overvoltage protection device is the thyristor surge protection device (TSPD) which is a solid-state electronic device typically used in crowbar protection circuits. Still another device used in protecting against overvoltage conditions is a silicon avalanche diode (SAD). SADs provide fairly fast limiting action of protection, but have very low energy absorbing capability, so are not useful in a lot of applications.